Instrument of patterning cusp for cardiac valve reconstruction and component thereof

ABSTRACT

In a case of repairing an aortic valve, etc. by forming a valve cusp with a biomembrane or the like, the shape and the size of a valve cusp can be determined easily. 
     An instrument including a valve cusp sizer  2  for measuring the sizer of the valve cusp and a template  3  for scribing lines for the shape of a valve cusp conforming to the measured size of the valve cusp, in which the valve cusp sizer  2  has a plurality of differently-sized sizer blocks (G 1  to G 8 ) attached to each of the top ends of grip members  21  respectively and each sizer block has an arcuate surface  24  formed by cutting each of differently-sized circular cylinders  22  at an angle conforming to the central angle for the commissure portions and, 
     the template  3  is formed with a scribing portion  31  including a substantially semi-circular valve cusp base forming portion  33  having a diameter as a sum of a nominal diameter (D 1  to D 8 ) defined for the diameter of a circular cylinder constituting the arcuate surface of a sizer block (G 1  to G 8 ) whose arcuate surface  24  conforms at both ends thereof to both of the commissure portions and an allowance for stitching margin (W), and a coaptation zone forming portion  34  in contiguous with the valve cusp base forming portion.

TECHNICAL FIELD

The present invention concerns an instrument for patterning a valve cuspand a component thereof, used for cardiac valve reconstruction thatstitches a valve cusp formed of an artificial membrane or a biomembraneto a portion of a tricuspid cardiac valve such as an aortic valve fromwhich an abnormal valve cusp has been excised. The instrument includes avalve cusp sizer for measuring the size of a valve cusp conforming tothe size of a cardiac valve and a template for scribing lines of a valvecusp shape on an artificial membrane or a biomembrane conforming to themeasured size of the valve cusp.

BACKGROUND ART

As shown in FIG. 8, a heart 71 has a function of a pump that sends ablood circulated through the body and flowing from superior and inferiorvena cava 72, 72 into a right atrium 73R from a right ventricle 74R byway of a pulmonary artery 75 to right and left lungs and then delivers ablood circulated from the lung by way of pulmonary veins 76 - - - to aleft atrium 73L from the left ventricle 74L by way of an aorta 10 to thewhole body.

For example, an aortic valve 11 is a cardiac valve that is formed at theexit where the blood flows out from the left ventricle 74L to the aorta10, in which cup-shaped three valve cusps 12, - - - of a thin membraneare present as shown in the schematic view of FIG. 9.

In each of the valve cusps 12, a portion defined along a commissureportion K of a cusp to a valve annulus on one end of a free margin F asan ON-OFF end→a bottom end C_(L) of a coaptation zone just therebelow→abottom B of the valve cusp→a bottom end C_(L) of the other coaptationzone→a commissure portion K of a cusp to a valve annulus on the otherend is integrated with the inner wall as valve annulus of the aorta 10to constitute a fixed edge 13.

Then, along with dilation and contraction of the heart 71, since thepressure in the left ventricle 74L becomes negative during diastole,coaptation zones Z_(c) formed on the side of the free margin F of thevalve cusps 12 are jointed to each other to close the valve 11 as shownin FIG. 9( a), whereas since the pressure in the left ventricle 74Lbecomes positive during cardiac systole, the coaptation zones Z_(c) ofthe valve cusps 12, 12, - - - are spaced apart from each other to openthe valve 11 as shown in Fig. (b).

However, when atheriosclerosis, etc. proceed along with aging andcalcium is deposited to calcify and harden the valve cusps, the valvecusps are restricted for the movement and do not open sufficiently tocause disease such as aortic valve stenosis.

According to the recent study, from 2 to 3% of the population of26,000,000 aged 65 years or older in Japan suffer from the disease.

When the aortic valve stenosis is caused, since pressure loss isgenerated at the affected area, the left ventricle intends to maintainthe blood pressure in the aorta at a normal 100 to 120 mmHg (duringcardiac systole) contracts at a pressure higher than that (for example,150 mmHg).

As a result, the left ventricle wall becomes thickened and causeshypertrophy and, when the thickness for the wall of the cardiac muscleis excessively increased, since the blood flow supplied from thecoronary arteries is no more sufficient, the heart becomes to ahypoalimentation and insufficient oxygen state (miocardial ischemia).Particularly, if myocardial ischemia is caused when the oxygen demand isincreased, for example, during activity, it may possibly cause symptomssuch as chest pain and syncope.

In a case where the blood pressure difference exceeds, for example, 50mmHg, this is judged as surgical indication.

The most popularized treatment is valve replacement by using aprosthetic valve.

The prosthetic valve includes two types, that is, a mechanical valveformed of carbon, graphite, etc. and a heterogenic biovalve preparedfrom biomembranes of animals such as swinery and cattle and they areoperated by the procedures as shown in FIG. 10.

That is, FIG. 10 is an explanatory view showing the outline ofprosthetic valve replacement. As shown in FIG. 10( a) to 10(b), allthree valve cusps (left coronary cusp, right coronary cusp, noncoronarycusp) 79, - - - of the aortic valve situated at the inlet of the aorta10 are excised while leaving only the valve annulus in contiguous fromthe left ventricle 74L to the aorta. Then, as shown in FIG. 10( c), theinner diameter of the aorta is measured by a sizer 81 as shown in FIG.10( c) (refer to Patent document 1) and a prosthetic valve 82 having avalve annulus outer diameter equal with the inner diameter of the aortais stitched to replace the valve.

[Patent Document 1] JP-T No. 2000-502937

However, even replacement is conducted by the prosthetic valve 82, sincethe prosthetic valve 82 has a shape in which the valve cusps 84 - - -are attached to a valve annulus 83, when it is stitched to the aorta 10,the inner diameter of the aorta 10 is decreased by so much as thethickness of the valve annulus 83 and the portion forms an orifice tocause pressure loss.

For example, in a case where the inner diameter of the aorta 10 is 20mm, when a prosthetic valve 82 having the valve annulus 83 of 3 mmthickness is mounted as the prosthetic valve, the inner diameter of theprosthetic valve 82 is decreased to 14 mm even when it is opened fullyand the area ratio is decreased to about ½. Then, a pressure loss iscaused to the portion and although the valve is replaced with an aim ofdecreasing the pressure loss caused by aortic stenosis, the loss cannotbe decreased sufficiently.

In a case of using a mechanical valve as the prosthetic valve 82, it isnecessary to continuously take an anti-coagulant agent such as warfarinfor whole life long, which results in a problem that it is difficult toarrest the bleeding in a case of injury, as well as, it is also pointedout a risk that teratogenesis may be caused possibly to a fetus when apregnant woman takes the agent.

On the other hand, there is no requirement of taking warfarin in a caseof using a heterogenic biovalve, but this involves a problem that thecost is as high as 1,000,000 yen or more per one valve unit.

Further, since both the mechanical valve and the heterogenic biovalveare obstacles after all, they may cause a risk of rejection.

Accordingly, as a result of an earnest study, the present inventor hasestablished, instead of valve replacement, an aortic valvereconstruction of repairing an aortic valve by decalcifying hardenedvalve cusps by using a supersonic surgical aspirator, etc., therebyleaving valve cusps that can be used as much as possible, and formingonly the valve cusp that is no more usable by using an autologuousbiomembrane, etc.

In this case, when the valve cusp is formed by incising an autologuouspericardium, etc., since this comprises an autologuous biobody tissue,there is no problem of causing the rejection or blood clotting reaction(thrombus) and there is no requirement of purchasing an expensiveprosthetic valve.

However, there has been a problem in this case how to cutout a valvecusp from a planar pericardium in the shape and the size conforming tothe diameter of a patient's aorta.

It is considered that the diameter (or radius) of the valve annuluscorresponds generally to the shape of the aorta. However, in a case ofmeasuring the diameter, for example, by a sizer 81 used for attachingthe prosthetic valve (refer to FIG. 10( c)), all valve cusps have to beexcised. If a usable valve cusp is left, the valve cusp hindersmeasurement for the diameter of the aorta.

Accordingly, the present inventor has attempted to use a model for theshape of the valve cusp based on the peripheral length of the valve cuspas shown in FIG. 11.

At first, assuming that an aorta is a circular cylinder having an innerdiameter (diameter) D and that the central angle for a free margin L_(F)extending from one commissure portion K of a cusp to a valve annulus,passing through the center P_(F) of the aorta to the other commissureportion K of the cusp to the valve annulus (central angle for thecommissure portions K, K) is 120° in a valve-open state, the length ofthe free margin is equal to D.

On the other hand, when assuming that the height from one commissureportion K to the bottom end C_(L) of the coaptation zone Z_(c) where thevalve cusps are joined to each other as h (usually the height isconsidered sufficient if h=10 to 12 mm), the coaptation zone Z_(c) has arectangular shape having a width L_(F) (=D) and a height h.

Since the central point P_(c) for the base B of the valve cusp is at aposition lower than the bottom end C_(L) of the coaptation zone, thelength L_(B) for the base of the valve cusp extending from the bottomend C_(L) of one commissure portion K, passing along the base of thevalve cusp through the central point P_(c) thereof to the bottom endC_(L) of the other coaptation zone is larger than the inner peripherallength of the aorta having the central angle of 120°.

Then, when the shape of the valve cusp is formed as asemi-circular-square shape comprising a semi-circular cusp base portionhaving a length L_(B) thereof up one-half circumference (=πr) of theinner periphery of an aorta and a rectangular portion corresponding to arectangular coaptation zone Z_(c) in contiguous therewith while makingan allowance for stitching formed by cutting out a pericardiumconforming to the shape and it is used for animal experiment of formingthe prosthetic valve cusp of an aortic valve, it showed good resultafter surgery.

In this case, if it is possible to easily measure the inner diameter Dof the aorta in a state of excising only one valve cusp, it is extremelyconvenient since the aortic valve can be formed while preparing thevalve cusp by cutting out the pericardium during surgery.

DISCLOSURE OF THE INVENTION Subject to be Solved by the Invention

The present invention has been achieved based on the inventor's findingas described above and, it intends to easily determine the shape and thesize of a valve cusp in a case of treating a tricuspid cardiac valvesuch as an aortic valve by replacing only the valve cusp that can nomore be used with an autologuous biomembrane or the like, therebyreconstructing the aortic valve.

Means for Solving the Subject

The present invention provides an instrument of patterning a valve cuspused for aortic valve reconstruction by stitching a valve cusp patternedfrom an artificial membrane or a biomembrane to a portion of a tricuspidcardiac valve such as an aortic valve from which an abnormal cusp hasbeen excised, the instrument including;

-   -   a valve cusp sizer for measuring the size of a valve cusp        conforming to the size of a cardiac valve, and    -   a template for scribing lines of the shape of the valve cusp on        the artificial membrane or the biomembrane conforming to the        measured size of the valve cusp, in which    -   the valve cusp sizer has a plurality of differently-sized sizer        blocks for measuring the length of a valve annulus extending        from one commissure portion of a valve cusp to a valve annulus        to the other commissure portion of the valve cusp to the valve        annulus of an excised valve cusp, where each of the seizer        blocks is attached to each of the top ends of grip members        respectively and each of the sizer blocks has an arcuate surface        formed by cutting each of differently-sized circular cylinders        at an angle conforming to the central angle for the commissure        portions and,    -   the template is formed with a scribing portion including a        substantially semi-circular valve cusp base forming portion        having a diameter as a sum of a nominal diameter defined for a        diameter of a circular cylinder constituting the arcuate surface        of a sizer block whose arcuate surface conform at both ends        thereof to both of the commissure portions of the excised valve        cusp when the cusp sizer is inserted to a valve annulus from        which the valve cusp has been excised and an allowance for        stitching margins, and a coaptation zone forming portion in        contiguous with the valve cusp base forming portion.

Effect of the Invention

According to the invention, the valve cusp sizer is inserted to thevalve annulus in a state of excising an abnormal valve cusp of atricuspid cardiac valve such as an aortic valve and, when the diameterof the sizer block whose arcuate surface conform at both ends thereof tothe commissure portions of the excised valve cusp, the diameter isdefined as a nominal diameter, and this is used as an index for decidingthe size of the valve cusp.

Since the scribing portion conforming to the nominal diameter is formedin the template, when a biomembrane, for example, a pericardium isextended, the template is put thereon, the shape of the a valve cusp isdrawn along the scribing portion by using, for example, a sterilizedsurgery skin marker, etc. and then the biomembrane is excised along theline, a prosthetic valve cusp conforming to the shape of the excisedvalve cusp is formed.

Then, when the thus formed prosthetic valve cusp is directly stitched tothe valve annulus where the base of the excised valve cusp has beenjoined, a tricuspid cardiac valve such as an aortic valve can be formedwithout decreasing the valve annulus thereof.

BRIEF EXPLANATION OF THE DRAWINGS

[FIG. 1] is an explanatory view showing an example of a valve cuspforming instrument according to the invention.

[FIG. 2] is an explanatory view showing a valve cusp sizer.

[FIG. 3] is an explanatory view showing a template.

[FIG. 4] is an explanatory view showing another embodiment of atemplate.

[FIG. 5( a)] is an explanatory view showing an aortic valve beforeexcising a valve cusp.

[FIG. 5( b)] is an explanatory view showing an aortic valve from which avalve cusp has been excised.

[FIG. 5( c)] is an explanatory view showing the state of measuring thesize of a valve cusp.

[FIG. 6] is an explanatory view showing the template in the state ofuse.

[FIG. 7] is an explanatory view showing a petri dish type vessel forpreparing each cusp individually.

[FIG. 8] is a schematic view of a heart.

[FIG. 9( a)] is an explanatory view showing an aortic valve in a closedstate.

[FIG. 9( b)] is an explanatory view showing an aortic valve in an openstate.

[FIG. 10( a)] is a view showing an aortic valve in which valve cusps arecalcified.

[FIG. 10( b)] is a view showing an aorta valve from which all valvecusps are excised.

[FIG. 10( c)] is a view showing the state of measuring the innerdiameter of an aortic valve by using an existent sizer.

[FIG. 10( d)] is a view showing an aorta replaced with a prostheticvalve by existent aortic valve replacement.

[FIG. 11] is an explanatory view showing a model of a valve cusp.

PREFERRED EMBODIMENTS OF THE INVENTION

The present invention intends to easily determine the shape and the sizeof a valve cusp in a case of reconstructing, a tricuspid cardiac valvesuch as an aortic valve by replacing only the valve cusp which is nomore usable using, an autologuous biomembrane, etc.

For this purpose, an instrument of patterning a valve cusp used foraortic valve reconstruction by stitching a valve cusp patterned from anartificial membrane or a biomembrane to a portion of a tricuspid cardiacvalve such as an aortic valve from which the abnormal cusp has beenexcised includes;

-   -   a valve cusp sizer for measuring the size of a valve cusp        conforming to the size of a cardiac valve, and    -   a template for scribing lines of the shape of the valve cusp on        the artificial membrane or the biomembrane conforming to the        measured size of the valve cusp.

The valve cusp sizer has a plurality of differently-sized sizer blocksfor measuring the length of a valve annulus extending from onecommissure portion of a cusp to a valve annulus to the other commissureportion of the cusp to the valve annulus of an excised valve cusp, whereeach of the seizer blocks is attached to each of the top ends of gripmembers respectively and each of the sizer blocks has with an arcuatesurface formed by cutting each of differently-sized circular cylindersat an angle conforming to the central angle for the commissure portions.

The template is formed with a scribing portion including a substantiallysemi-circular valve cusp base forming portion having a diameter as a sumof a nominal diameter defined as a diameter of a circular cylinderconstituting the arcuate surface of a sizer block whose arcuate surfaceconform at both ends thereof to both of the commissure portions of theexcised valve cusp when the cusp sizer is inserted to a valve annulusfrom which the valve cusp has been excised and an allowance forstitching margins, and a coaptation zone forming portion in contiguouswith the valve cusp base forming portion.

First Embodiment

FIG. 1 shows an instrument 1 of this embodiment which includes a valvecusp sizer 2 for measuring the size of a valve cusp conforming to thesize of a cardiac valve, a template 3 for scribing lines of a shape ofthe valve cusp on an artificial membrane or a biomembrane conforming tothe measured size of the valve cusp, and a base plate 4 for maintainingthe artificial membrane or the biomembrane in a planar state uponscribing the lines for the shape of the cusp by using the template 3.

The valve cusp sizer 2, the template 3, and the base plate 4 arecontained in a stainless steel case 5, and they can be sterilized in astate as they are contained therein by an sterilizing autoclave.

In the case 5, a main body 51 for containing the valve cusp sizer 2, anda cover 52 for containing the template 3 and the base plate 4 are openedand closed by a hinge 53, and a partition plate 54 is disposedtherebetween.

The cusp sizer 2 has a plurality of differently-sized sizer blocks G₁ toG₈ for measuring the length of the valve annulus from one commissureportion of a valve cusp to a valve annulus to another commissure portionof the valve cusp to the valve annulus of an excised valve cusp, andeach of the sizer blocks is attached to each of the top ends of gripmembers 21, 21, - - - .

Then, as shown in FIG. 2, each of the sizer blocks G₁ to G₈ has, as abasic shape, a partial circular cylinder 23 formed by cuttingdifferent-sized circular cylinder 22 at an angle conforming to thecentral angle for the commissure portions of the aortic valve (120° inthis embodiment, while assuming that the central angles for threecommissure portions K are equal).

The outer peripheral surface is formed as an arcuate surface 24 to beabutted against the valve annuls of an aorta from which an abnormalvalve cusp has been excised, and contact probe portions 25 of apredetermined length for positioning and abutting both ends of thearcuate surface 24 against the commissure portions K, K are formed inparallel with the central axis of the arcuate surface 24.

The diameter of the circular cylinder 22 (arcuate surface 24) is used asthe nominal diameter (D₁ to D₈) for defining the size of the valve cusp.In this embodiment, sizer blocks G₁ to G₈ having eight types of nominaldiameters D₁ to D₈ from 17 to 31 mm on every 2 mm step are used whileconsidering the personal differences for the diameter of adult aorta.

Then, numerical values for the nominal diameters D₁ to D₈ are indentedto the grip members 21 such that the size of the sizer block D₁ to D₈attached to the top ends thereof can be read.

Further, the central point P_(c) for the base B of the valve cusp is ata position lower than the bottom end C_(L) of a coaptation zone (referto FIG. 11). Therefore, the upper surface 26 for each of the sizerblocks G₁ to G₈ is formed being curved in a concave shape such that thecentral point P_(c) for the base B of the valve cusp between thecommissures portions K, K where the valve cusp is to be stitched can beseen when each of the contact probe portions 25 is abutted against eachof the commissure portions K, K from which the valve cusp has beenexcised.

Further, an index 27 as a center marker for defining the central pointP_(c) is formed at a position of the upper surface thereof correspondingto the central point P_(c) in a case of starting stitching from thecentral point P_(c).

Then, the grip member 21 is attached to the center of the partialcircular cylinder 23 that forms each of the sizer blocks G₁ to G₈ suchthat it does not hinder the observation of the valve annulus in a stateof abutting the arcuate surface 24 of each of the sizer blocks G₁ to G₄to the valve annulus, and the grip member 21 is inclined by apredetermined angle θ (θ=30°) in this embodiment) relative to thecentral axis X to the side opposite to the arcuate surface.

FIG. 3 shows the template 3 which is put over the artificial membrane orthe biomembrane for scribing the lines of the shape of the valve cusp byusing a sterilized surgery skin marker, etc. and in which a plurality ofscribing portions 31 having differently-sized shapes of the valve cuspare perforated.

The scribing portion 31 is formed as a semi-circular-rectangular partcomprising a substantially semi-circular base forming portion 32 and asubstantially rectangular coaptation forming portion 33 in contiguoustherewith.

When assuming that a valve cusp sizer 2 is inserted to a valve annulusfrom which a valve cusp has been excised and that contact probes 25formed on both ends of the arcuate surface of a sizer block Gn (G₁ toG₈) conform to both of the commissure portions of the excised valvecusp, the valve cusp base forming portion 32 has a diameter as a sum ofthe diameter defined as a nominal diameter Dn of the circular cylinderand an allowance for stitching margins 2W on both right and left sides(Dn+2 w). The stitching margin is designed as: w=3 mm in thisembodiment.

Further, the coaptation zone forming portion 33 is formed as arectangular shape having a width equal with the diameter of the cuspbase forming portion 32 from both ends of the cusp base forming portion32 to the free margin portion 34 at the top end, and having a length hof 12 mm which is necessary and sufficient as the height for thecoaptation zone.

Then, nominal diameters D₁ to D₈ are described as guide numbers forrespective scribing portions 31. Thus, the scribing portion 31conforming to the measured nominal diameter Dn of the aorta measured bythe cusp sizer 2 can be selected easily.

FIG. 4 shows another improved template 6, in which the shape of thescribing portions 61 - - - is improved for further decreasing the backflow blood.

This embodiment is identical with the first embodiment in that a cuspbase forming portion 62 is formed of a semi-circle having a diameter asa sum of the nominal diameter Dn and an allowance for the stitchingmargins 2 w on both right and left sides (Dn+2 w).

A coaptation zone forming portion 63 is formed as a pentagonal shape inwhich both end edges thereof are extended for a length h conforming tothe height of the coaptation till it reaches the free margin 64 at thetop end while being gradually widened from both ends of thesemi-circular cusp base forming portion 62, and the center of the freemargin portion 64 at the top end thereof is protruded into an angledshape.

In this embodiment, the maximum width α of the coaptation zone formingportion 62 is designed as: α=1 mm and the protrusion length β at thecenter of the free margin portion 64 is designed as: β=2 to 3 mm.

In this embodiment, an allowance is provided for the length of the freemargin portion 64 by gradually increasing the width thereof whilemaintaining the substantially rectangular shape as the coaptation zoneforming portion 63, and air tightness is improved when the valve cuspsare closed to reliably prevent backflow of the blood by increasing theheight for the central portion where three valve cusps are in contactwith each other.

The base plate 4 is formed, for example, of a stainless steel plate inwhich perforations 41 are formed at the periphery thereof for puttingand stretching threads 43 that are passed through the biomembrane or theartificial membrane (refer to FIG. 1, FIG. 6).

The constitution of the embodiment of the present invention is as hasbeen described above and the operation thereof is to be described to anexample for the treatment of aortic valve stenosis with reference toFIG. 5 and FIG. 6.

Aortic valve reconstruction is applied, for example, by leaving twovalve cusps 12, 12 that can function normally by removing a calciumcomponent by a supersonic surgical aspirator as they are and replacingonly one valve cusp 12 a that cannot be repaired by decalcification witha prosthetic valve cusp formed of an autologuous pericardium among threevalve cusps 12 of an aortic valve 11 suffering from aortic valvestenosis caused by deposition and calcification of calcium.

In this case, skins, subcutis, and fascia are at first incised toexteriorize sternum, which is subjected to medium sternotomy and thenthe pericardium is incised. Then, extracorporeal circulation is startedby a pump oxygenator in a state of exposing the heart and, afterstopping cardiac activity, the aortic valve 11 is exposed on the side ofthe aorta.

Then, the pericardium is incised into an appropriate size and thepericardium 42 is extended over the base plate 4 and dipped in ahistological fixture such as glutaraldehyde in a fixed state by puttingaround threads 43.

Then, as shown in FIG. 5( a) to (b), among three valve cusps 12, - - -of the aortic valve 11, one valve cusp 12 a is excised by applying asurgical knife along the fixing edge 13 thereof, a cusp sizer 2 isinserted to the portion as shown in FIG. 5( c) to measure the size ofthe excised valve cusp 12 a.

Specifically, differently-sized sizer blocks G₁ to G₈ of the cusp sizer2 are inserted successively and abutted to the valve annulus of theaorta 10 from which the valve cusp 12 a has been excised, and a sizerblock Gn in which the contact probe portions 25 disposed on both ends ofthe arcuate surface 24 thereof conform to both of the commissureportions K, K of the excised valve cusp 12 a is confirmed and thenominal diameter Dn for the cusp sizer 2 is read.

When the nominal diameter Dn that determines the cusp size is decided,the pericardium 42 dipped in glutaraldehyde is taken out together withthe base plate 4, over which the template 3(6) is placed, and lines forthe cusp shape is drawn along the inner peripheral surface of thescribing portion 31 (61) conforming to the nominal diameter Dn on theautologuous pericardium 42 by a skin marker 44. Then, it is detachedfrom the base plate 4 and cut into the scribed shape by a shear sizerand dipped in physiological saline for preventing drying.

In a case of forming, for example, only one valve cusp, the valve cuspformed of the pericardium 42 may be dipped in a vessel such as a tray ora Petri dish containing physiological saline. However, the tricuspidvalve of the aortic valve includes three members of right coronary valvecusp, left coronary valve cusp, and non-coronary valve cusp. In a caseof forming two or more of them and if the size of respective cusps aredifferent subtly, when they are happened to be stitched erroneously,this brings about a trouble in the aortic valve reconstruction.

In order to prevent this, as shown, for example, in FIG. 7, a petri dishtype vessel 7 for preparing each cusp individually is used. The vesselis partitioned into three parts of a right coronary cusp dipping portion8R, a left coronary cusp dipping portion 8L, and a non-coronary cuspdipping portion 8N by partition walls 7 a, and identification tags 9R,9L, 9N are attached for identifying respective dipping portions 8R, 8L,8N. By filling the respective dipping portions 8R, 8L, 8N withphysiological saline and dipping valve cusps formed of the pericardium42 into respective dipping portions 8R, 8L, 8N, a risk of erroneouslystitching them during surgery can be prevented.

Then, when the valve cusp can be formed from the autologuous pericardium42, the cusp sizer 2 having the nominal diameter Dn is again abutted soas to conform the contact probe portions 25 thereof to both commissureportions K, K of the excised valve cusp 12 a, a thread is put to a valveannulus at a position indicated by an index 27 formed to a positioncorresponding to the central point P_(c) of the base B of the valve cuspwith reference to the index 27, the central point P_(c) of the base B ofthe valve cusp is stitched and then they are stitched successivelytoward respective commissure portions K, K with the point Pc as areference.

Thus, the aortic valve can be reconstructed by stitching a valve cuspformed of the autologuous pericardium to a portion where the valve cusp12 a has been excised.

Since the valve cusp formed as described above is made of theautologuous pericardium, it does not cause rejection. Further, since thevalve annulus of the aortic valve can be utilized as it is, noadditional valve annulus is formed and projected into the aorta and,accordingly, the pressure loss during opening of the valve is extremelysmall.

While the description has been made to a case of forming the valve cuspwith the pericardium, the present invention can be applied also to acase of forming the valve cusp with a heterogenic biomembranes ofanimals such as cattle, horses and swinery, as well as with artificialmembranes.

INDUSTRIAL APPLICABILITY

As has been described above, the present invention is applicable use offorming a valve cusp of optimal size and shape upon treatment ofabnormal valve cusp syndrome by cardiac valve reconstruction ofstitching a valve cusp formed of an artificial membrane or a biomembraneto a portion of a tricuspid cardiac valve such as an aortic valve fromwhich an abnormal valve cusp has been excised.

DESCRIPTION OF THE REFERENCES

1 valve cusp forming instrument

2 valve cusp sizer

3 template

G₁ to G₈ sizer block

21 grip member

22 circular cylinder

24 arcuate surface

25 contact probe portion

31 scribing portion

32 valve cusp base forming portion

33 coaptation zone forming portion

D₁ to D₈ nominal diameter

1. An instrument of patterning a valve cusp used for aortic valve reconstruction by stitching a valve cusp patterned from an artificial membrane or a biomembrane to a portion of a tricuspid cardiac valve such as an aortic valve from which an abnormal cusp has been excised, the instrument including; a valve cusp sizer for measuring the size of a valve cusp conforming to the size of a cardiac valve, and a template for scribing lines of the shape of the valve cusp on the artificial membrane or the biomembrane conforming to the measured size of the valve cusp, in which the valve cusp sizer has a plurality of differently-sized sizer blocks for measuring the length of a valve annulus extending from one commissure portion of a valve cusp to a valve annulus to the other commissure portion of the valve cusp to the valve annulus of an excised valve cusp, where each of the seizer blocks is attached to each of the top ends of grip members respectively and each of the sizer blocks has an arcuate surface formed by cutting each of differently-sized circular cylinders at an angle conforming to the central angle for the commissure portions and, the template is formed with a scribing portion including a substantially semi-circular valve cusp base forming portion having a diameter as a sum of a nominal diameter defined for a diameter of a circular cylinder constituting the arcuate surface of a sizer block whose arcuate surface conform at both ends thereof to both of the commissure portions of the excised valve cusp when the cusp sizer is inserted to a valve annulus from which the valve cusp has been excised and an allowance for stitching margins, and a coaptation zone forming portion in contiguous with the valve cusp base forming portion.
 2. A valve cusp sizer for measuring the size of a valve cusp conforming to the size of a cardiac valve in a cardiac valve reconstruction of reconstructing a cardiac valve by stitching a valve cusp which is formed by pattering an artificial membrane or a biomembrane, to a portion of a tricuspid cardiac valve, for example, of an aortic valve from which an abnormal valve cusp has been excised in which each of a plurality of differently-sized sizer blocks for measuring the length of a valve annulus extending from one commissure portion of a valve cusp to a valve annulus to the other commissure portion of the valve cusp to the valve annulus of an excised valve cusp is attached to the top end of each of grip members, and an arcuate surface formed by cutting a circular cylinder of different radius at an angle conforming to the central angle for the commissure portion is formed to each of the sizer blocks.
 3. A valve cusp sizer according to claim 2, wherein contact probe portions for positioning both ends of the arcuate surface of the sizer block to the commissure portions are formed in parallel with the central axis of the arcuate surface.
 4. A valve cusp sizer according to claim 2, wherein the upper surface of the sizer block is formed being curved as a concave shape such that the central point for the valve cusp base between commissure portions can be observed when both ends of the arcuate surface of the sizer block are abutted against both of the commissure portions of the valve annulus from which the valve cusp has been excised.
 5. A valve cusp sizer according to claim 3, wherein the upper surface of the sizer block is formed being curved as a concave shape such that the central point for the valve cusp base between commissure portions can be observed when both ends of the arcuate surface of the sizer block are abutted against both of the commissure portions of the valve annulus from which the valve cusp has been excised.
 6. A valve cusp sizer according to claim 4, wherein an index as a center marker is attached to the upper surface of the sizer block at a position corresponding to the central point of the valve cusp base between commissure portions.
 7. A valve cusp sizer according to claim 5, wherein an index as a center marker is attached to the upper surface of the sizer block to a position corresponding to the central point of the valve cusp base between the commissure portions.
 8. A valve cusp sizer according to claim 2, wherein the grip member is attached to the center of the circular cylinder that forms the sizer block and inclined relative to the central axis thereof at a predetermined angle on the side opposite to the arcuate surface.
 9. A template for scribing lines of a valve cusp shape on an artificial membrane or a biomembrane conforming to shape of a valve cusp, in which a valve cusp sizer for measuring the size of the valve cusp has a plurality of differently-sized sizer blocks for measuring the length of a valve annulus extending from one commissure portion of a cusp to a valve annulus to the other commissure portion of the cusp to the valve annulus of an excised valve cusp, where each of the seizer blocks is attached to each of the top ends of grip members respectively and each of the sizer blocks is formed with an arcuate surface formed by cutting each of differently-sized circular cylinders at an angle conforming to the central angle for the commissure portions and, the template is formed with a scribing portion including a substantially semi-circular valve cusp base forming portion having a diameter as a sum of a nominal diameter that is defined for a diameter of a circular cylinder constituting the arcuate surface of a sizer block and stitching margins, and a coaptation zone forming portion in contiguous with the valve cusp base forming portion.
 10. A template according to claim 9, wherein the coaptation zone forming portion is formed into a rectangular shape in which both end edges thereof are extended from both ends of the valve cusp base forming portion for a length conforming to the height of the coaptation.
 11. A template according to claim 9, wherein both ends edges of the coaptation zone forming portion are extended for a length conforming to the height of the coaptation zone while being widened gradually from both ends thereof and the free margin portion at the top end is formed into an angled shape. 